The envelope
Roofing Squares Calculator
Enter your roof's footprint (the ground area it covers) and pick your pitch. A steeper roof has more surface than its footprint. One roofing square is 100 square feet.
At a glance
- Covers per square
- 100 sq ft
- Waste allowance
- +12%
- Answer in
- squares
100 sq ft needs:
1.2 squares
Includes a 12% allowance for waste.
One square = 100 sq ft. We add 12% for waste and cuts; complex roofs with lots of hips and valleys need more. Get on a ladder only if it's safe. A roofer measures this for the real order.
The envelope
The envelope works as one system
A roof that sheds fine into gutters that overflow still rots the fascia underneath. When one part is due, it is worth pricing the parts next to it at the same time.
How this is worked out
No hidden fudge factor. This is the whole calculation.
- Length times width gives the area in square feet.
- That area is divided by 100 square feet, which is what one covers, to give the squares.
- Roof pitch scales the area, since a steeper surface has more of it than its footprint.
- A 12% allowance is added on top for cuts, offcuts and odd shapes.
Common questions
- How much roofing do I need?
- Enter your roof's footprint (the ground area it covers) and pick your pitch. A steeper roof has more surface than its footprint. One roofing square is 100 square feet. Enter your measurements above and this calculator gives you the amount, including a waste allowance where it applies.